


Definitive edition works excellent on Deck. Very minor technical hiccups aside, game runs right out of the gate without configuration.
A few times across the whole playthrough combat would randomly slow to a crawl. Extremely infrequent.
Game crashed exactly once across my whole playthrough. Didn't lose any progress, but might have been frustrating if it had happened with worse timing.

Game works great if you use Proton. You technically can play the Native version, but you won't get the new Definitive Edition content.
5 Watts, 200 GPU
Used Proton 8.0-2, listing it here since you STILL can't mark that as a version on here. Tested Painful up to the first save point and haven't tested Joyful.
Only problem was during Dismal Island where I had to modify Brad's name, I had to press "X" on my Bluetooth keyboard just to delete characters because it didn't recognize the Steam Deck's virtual keyboard. Maybe mapping a "X" button on your controller layout could work as well but can't confirm.
Map Alt+Enter to full screen the game when you start. It won't remember that you had it full screen last time. This is important for Steam Deck users who have no real keyboard.
Some text is pretty small and may be hard for some to read.
If for any reason you need to use F1 to change something, do it in Desktop Mode. Game Mode has issues with Gamescope because this is an additional window.
Yes, Steam Deck can't Alt-Enter to full screen unless you map something to that.